Fixed! Started another thread (https://forum.sequential.com/index.php/topic,7604.0.html), but long story short it ended up being a dead CR2032 battery. Thats it. couple of bucks at home and were good.
The battery has caused me pain too. Apparently, there's an update Firmware that removes the requirement for a battery.
I'm too scared to try it yet as my X is working (touch wooden end cheeks) ... but the 5.2 V change appears to have done a lot of good.
Stephen